The instant invention concerns a socket capping for a fluorescent tube with a cylindrical glass tube, having gas-tightly sealed end portions which are penetrated by connection wires. Each end of the tube generally has an annular collar, the outer side of which is provided with an encircling groove. A socket capping having an internal annular wall is fitted onto the groove. The capping consists of an elastic, bendable thermoplastic material, and carries contact pins at its front portion which are connected with the connection wires. The annular wall mounts on the collar so as to be secured against being pulled off or twisted. For this, the annular wall is provided on its inside portion with at least one protrusion which, under elastic deformation of the annular wall, is pushed onto the collar and snaps into position in the groove.
In a prior art fluorescent tube, the synthetic material from which the socket capping is made is a brittle, hard duroplastic material and the inside of the annular wall is cylindrically smooth. The collar, over its entire circumference, is glued to the annular wall by means of a putty which fills the groove. The putty requires several hours to dry at relatively high temperatures. This putty-connection of the annular wall of the socket capping and the collar of the glass tube, even though securing the capping against twisting and against being pulled off even with normal tolerance deviations in the measurements of annular wall and collar, is costly in production. This is because not only must putty be applied, but also, in order to reduce the hardening or drying time, one must work with an increased temperature of more than 80.degree. C. Thus, the socket end of the fluorescent tube is heated over a prolonged period of time by means of gas flames. This makes the process of producing these uneconomical because of the use of fuel and the additional time.